In general, a tire is manufactured through processes such as a semi-product process for producing parts respectively having quality in accordance with their property and use, a forming process for assembling different parts to form a semi-produced tire, and a curing process for curing the semi-produced tire in a mold. The manufactured tire is assembled with a separately manufactured wheel and used as a pneumatic tire.
FIG. 1 is a sectional view of a conventional tire which is manufactured by assembling a plurality of semi-produced parts and then curing the assembled semi-produced parts, and the conventional tire includes semi-produced parts, such as an inner liner 101, a carcass 102, a belt 103, a belt cushion 104, a capply 105, a tread 106, a sidewall 107, a bead 108 and a bead filler 109.
The inner liner 101 is disposed in the tire to prevent the leakage of the air. The carcass 102 is a cord layer in the tire, which is a part for supporting a load, for enduring an impact, and for having fatigue resistance to an extension and contraction movement during the driving. On the other hand, the belt 103, which is disposed between the tread 106 and the carcass 102, is made of steel wires in order to reduce outer impact and to make the tread widely contact the ground resulting in improving the driving stability. The belt cushion 104 is partly disposed between the layers of the belt. The capply 105 is a specific cord sheet disposed on the belt of a radial tire, which is a part for minimizing the movement of the belt during the driving. In addition, the tread 106 is in direct contact with the ground and provides the tire with friction force necessary for braking and driving. Therefore, the tread 106 must have excellent durability against abrasion, endure outer impact, and have a low heat generation property. The sidewall 107 is a rubber layer positioned at a side portion of the tire, which has durability against the extension and contraction movement of the tire in order to protect the carcass in the tire. The bead 108 is a bundle of wires having a square section or hexagonal section and being made of steel wires coated with rubber, which is used as a part holding and fixing the tire to the rim of the tire. The bead filler 109 is material made of rubber in order to minimize dispersion of the bead and to reduce the outer impact, resulting in protecting the bead.
As described above, the pneumatic tire made of a plurality of semi-products has disadvantages in that the tire performance can be reduced due to weight imbalance or adhesion of the semi-products, or due to heat generation caused by friction, and that the tire may be punctured during the driving to make the vehicle fail to drive consistently.
In order to improve the disadvantages of the prior pneumatic tire, a run-flat tire is developed and provided. The run-flat tire can make a vehicle drive consistently for a constant time even if the run-flat tire is punctured. Thereby, a driver can safely move the vehicle to a garage to repair the tire.
The conventional run-flat tire may have different structures. FIG. 2 is a photograph showing sections of a general pneumatic tire and a run-flat tire in which reinforced rubber is strengthened on an inner side of a sidewall of the run-flat tire, as comparing sections with each other. It can be known that the run-flat tire has a sidewall thicker than that of the general pneumatic tire in order to improve durability against an extension and contraction movement.
Furthermore, a supporting ring made of a rubber material is additionally mounted on an outer peripheral surface of the wheel in the pneumatic tire in order to temporarily endure a load applied to the wheel when the tire is punctured. On the other hand, a supporting ring made of a metal material is mounted on the inner surface of the pneumatic tire while protruding from the inside of the pneumatic tire toward the wheel, in order to temporarily endure a load applied to the wheel when the tire is punctured. Accordingly, the vehicle can be temporarily driven without damage to the wheel.
In the above mentioned run-flat tire, there are problems in that the run-flat tire has increased weight because the supporting ring made of a rubber or metal material is mounted or an additional structure is reinforced, thereby reducing a basic performance of the tire and lowering fuel efficiency during the driving of the vehicle, and in that the run-flat tire increases fatigue of important semi-products constructing the tire when the vehicle is driven in a condition of tire puncture, so as to fail to return to a state before the tire puncture, to provide abnormal performance, and to be impossible to be recycled.
The present applicant has proposed a method for manufacturing a non-pneumatic tire integrated with a wheel in Korean Patent No. 1030505 issued to the present applicant. Referring to FIG. 3, the tire 110 integrated with the wheel according to the above-mentioned Korean Patent includes a wheel 111 having a rim 112 formed thereon and rim flanges 113 protruding from both sides of the rim 112, which respectively have an end portion bent outwardly, and a tread 114 formed on the rim to cover an outer peripheral surface of the rim flange, which has a convex surface and tread patterns formed on an outer surface thereof.
The above-mentioned registered patent has advantages in that it is not concerned with a puncture of the tire because of the non-pneumatic tire having the tread integrally formed on the wheel, and in that it is possible to improve the driving performance during the driving because it is not necessary to reinforce a side rubber and to add a support ring such that the side rubber is reinforced on the run-flat tire, resulting in reducing the weight of the tire. However, the tire according to the registered patent has a disadvantage in that ride comfort can be reduced because the tread contacting with a road is formed on the wheel so as to directly transfer impact loading from the road to the wheel.